Flow controlling valve means for hydraulic motors



Nov. 18, 1947. w. ERNST 2,431,032

FLOW CONTROLLING VALVE MEANS FOR HYDRAULIC MOTORS Filed April 5, 1943 INVENTOR WALTER skusr,

BY W1 ATTORNEYS Patented Nov. 18, 1947 FLOW CONTROLLING VALVE MEANS FOR HYDRAULIC MOTORS Walter Ernst, Mount Gilead, Ohio, assignor to H-P-M Development Co of Delaware rporation, a corporation.

Application April 5, 1943, Serial No. 481,798

Claims.

This invention relates to hydraulic machinery and, in particular, to hydraulic systems including a fluid operable reciprocable plunger.

If, in hydraulic systems of this ty it is desired to move the plunger at a high speed during a portion of its working stroke and subsequently at,

a lower speed during the successive portion of the working stroke, it was heretofore customary to provide the cylinder, in which the said plunger reciprocates, with surge valve means which automatically establish a fluid connection between a fluid reservoir and the advancing side of the plunger, to pre-fill the adjacent portion of the cylinder. The said surge valve is so arranged as to interrupt the fluid connection between the advancing side of the said plunger and the fluid reservoir, as soon as the plunger encounters a predetermined resistance. In some instances, prefilling pumps were heretofore provided for prefilling the cylinder in which the fluid operable plunger reciprocates.

It is an object of this invention to provide a hydraulic system of the "above type, in which, however, no surge valve means or pre-fllling pumps are required for prefilling the cylinder portion adjacent the advancing side of the working plunger.

It is another object to provide a hydraulic system, including a reciprocable plunger having associated therewith fluid operable advancing and retracting means, in which, during the initial portion of the working stroke of the said plunger, a fluid connection is automatically established between the retracting means and the advancingmeans, while, during the subsequent portion of the working stroke of said plunger, the said fluid connection is automatically interrupted.

the control means are made ineflective during the retracting stroke of the plunger.

These and other objects and advantages will appear more clearly from the following speciflca tion in connection with the accompanying drawing illustrating a hydraulic system according to the invention.

General arrangement means being provided for reciprocating said plunger. The retracting means is hydraulically connected with a control valve which, during the initial portion 01' the advancing stroke prevents the escape of fluid from the retracting means to an exhaust. while low Pressure responsive means. is adapted during this period, to establish fluid connection between the retracting means and the advancing means.

When a predetermined pressure has built up at the advancing means, this pressure actuates the control means to cause the latter to effect fluid connection between said retracting means and an exhaust, thereby making said low pressure It is a, still further object of this invention to,

provide a hydraulic system, including a plunger having associated therewith fluid operable advancing and retracting means for reciprocating said plunger, in which low pressure responsive valve means associated with said retracting means is adapted, in response to a low pressure acting thereupon, to eifect fluid connection between said advancing and said retracting means, whereas control means is associated with the said advancing means making said low pressure responsive means ineifective and connecting said retracting means with an exhaust when a predetermined high Pressure .acts on said advancing 1 means.

It is still another object to provide a hydraulic responsive means ineflfective and interrupting fluid connection between said retracting means and said advancing means.

Structural arrangement Referring now to the drawings in detail, the structure shown therein comprises a cylinder, generally designated I, having a bore 2 in which is reciprocably mounted a plunger 3. The plunger 3 has a piston portion 4 with a large advancing, area 5 and a smaller retracting area 6. The plunger 3 is provided with a threaded portion 1 for connection with a member or element to be controlled. The right hand portion of the cylinder bore 2 is connected with a passageway 8 adapted to communicate with a passageway or channel 9 provided in the cylinder I. The fluid communication between the passageway Band the channel 9 is controlled by a controlplunger ll) of a low pressure valve, which plunger has associated therewith a piston portion ll acted upon into closing position. The spring casing it communicates with a conduit l4 leading into a conduit l5. The conduit 15. which comprises a' check valve It, has one end thereof connected to a 4-way valve, generally designated IT. The valve l1, which may be of anystandard type, has connected thereto a conduit l8 leading to the right hand end of the cylinder bore 2. Also connected to the valve I1 is a pressure line 19 leading to the pressure side of a fluid pressure source 20, such as a pump, the suction side ofwh ich is connected through a conduit 2| with a fluidreservoir or tank 22. v i I The tank '22 communicates through an exhaust line 23 with the valve H. The valve I1 is operable by means of the handle 24 so that when-the handle 24 is moved into its upper position, the conduit l8 communicates with the pressure line exhaust line 23.

The left hand portion of the cylinder bore-2 communicates with a passageway 25 adapted to Therefore, the onlyway of escape for the fluid from the left hand portion of the cylinder bowl is through the passageway 25. Consequently, the fluid acted upon by the retractionarea 6 and sub- .jected to a slight pressure opens the check valve =9 is sufficient to overcomethe thrust of the spring l2 and to move the control plunger 10 toward the communicate with the channel'9. The fluid connection between the passageway and the channel 3 is controlled by a check valve 26. The left end portion ofthe cylinder bore 2 furthermore communicates through a bore 21 with a conduit 28 leading to a high pressure valve, generally designated 28. through a conduit 30 with the tank 22, comprises a valve bore 3| having reciprocably mounted therein a valve member 32. The valve member 32 The valve 28, which is connected is provided with two piston portions 33 and 34, of i the same effective area.

The piston portion 34 is acted upon by a relatively strong spring 35 which continuously dress the valve member 32 toward; the right to thereby cause the piston portion 33 to abut'the plug 36. The plug'36 is provided with a bore 31 therethrough which communicates with a conduit 38. The conduit 38 branches out into a conduit '39 comprising an adjustable choke 40 and a conduit 4! comprising a check valve .42. The conduits 39 and 4| then converge into the pilot line 43 communicating with the conduit l8. The valve 29 is furthermore provided with a breather opening.

Operation It may be assumed that all parts occup the position shown in the drawing while thehandle 24 occupies its intermediate or neutral position, in which fluid connection between the pressure right sothat fluid communication is established between the passageway 9 and the right hand end of the cylinder bore 2. v It will, therefore, be clear that, during the initial leftward movement of the plunger 3, the fluid expelled from the left hand portion of the cylinder bore 2 is conveyed to the right hand portion thereof, thereby pre-fllling the latterand speeding up the advancing movement of the plunger 3.

As soon as, during the leftward movement of the plunger 3 the latter encounters resistance, the pressure in the'left end of the bore 2 drops and pressure builds up inthe conduit l8, which pressure is conveyed through the pilot line 43, the check valve 42 and the conduit 38 to the right hand end of the valv bore 3| where it acts upon the piston portion 33 and causes the valve mem-- ber 32 to move leftwardly against the thrust of the spring 35. In this way, fluid connection is established betweenthe conduit," andthe conduit 30 leadingto the tank 22. As a result thereof, the fluid expelled from the left hand portion of the cylinder bore 2 can escape into the tank 22 and the pressure in the left hand portion of the cylinder bore 2 drops immediately.

In view of the drop in pressure in. the left end of the bore 2, the check valve 28 again moves into its closing position. The'movement of the control plunger l0 into its closing position may be effected by the spring l2 but it will be apparent line l9 and either of the conduits l5 and l 8 is prcvented. 1 In order to start a workingstroke of the plunger 3, the operator shifts the handle 24 into its upper position to thereby connect the pressure line I! with the conduit l8, while simultaneously connecting the conduit l5 with the exhaust line 23. Pressure fluid delivered by the fluid source 20 then passes through the pressure line IS, the

valve I1 and the conduit l8lnto the right hand portion of the cy1inderbore2 where it acts upon the advancing area '5 of the piston portion 4.

As a result thereof, the plunger 3 moves toward the left. During this initial leftward movement of the plunger 3, which latter, it may be assumed,

does not encounter any resistance during this initial movement, no fluid can escape from the lefthand portion of the cylinder bore 2 through conduit 28 into the conduit 30 because the valve member 32 prevents such fluid communication.

- hand ends of the bore 2.

that th closing of the check valve 28 is willcient hydraulically to isolate the right and left Therefore, the plunger 3 now performs itsworking stroke at a. reduced speed. If during this working stroke, slight pressure fluctuations should occur in the pilot line 43, this will not cause a fluttering of the valve member 32, since the choke 4llmaintains a predetermined pressure in the conduit 38 sufllcient to hold the valve member 32 into position for establishing fluid connection between the conduits 28 and 30.

When the plunger 3 has reached the desired end of its leftward movement, the handle 24 is moved into its lower position, to thereby establish fluid connection between the pressure line 3 and the conduit l5, while simultaneously effecting fluid connection between the conduit l8 and the exhaust line 23. Consequently, pressure fluid delivered bythe fluid source 20 now passes through the pressure line [9, the conduit l5, check valve l6, conduit-28 and bore '21 into the left hand portion of the cylinder bore 2 where it acts upon the retraction area 6 and causes the plunger 3 to move toward the right. The fluid expelled from the right hand portion of the cylinder bore 2, during this rightward movement of the plunger 3, escapes through conduit I 8 into the exhaust in the' conduit 38 drops and the spring 35 commences to return the valve, member -32 into the position shown in the drawing, this being accomplishedin a relatively short time, and being effective to interrupt fluid connection between the conduit 28 and the conduit 30. When the plunger of the plunger 3 during the retraction stroke thereof will open the check valve 26, and be conveyed into the passageway 93. It will, however, be prevented from moving. the plunger Hi rightwardly by the pressure conveyed through the conduit [4 and acting upon the piston portion I i.

While the invention has been described in connection with a horizontally. moving plunger, it will be clear that the invention may equally well be applied to a vertically reciprocable plunger.

It is, of course, understood that the present invention is by no means limited to the particular arrangement shown in the drawing. but also embraces such modifications as come within the scope of the appended claims.

Having thus fully described and ascertained the nature of my said invention, what I claim as new and desire to secure by Letters Patent is:

1. In a hydraulic system, a plunger, fluid opera able advancing and retracting means associated with said plunger for reciprocating the same, low pressure responsive means associated with said retracting means and responsive to a low pressure acting thereupon to effect fluid connection between said advancing and said retracting means, and high pressure responsive means also associated with said retracting means and operable in response to a predetermined high pressure acting on said advancing means to connect said retracting means with an exhaust to make said low pressure responsive means ineffective.

2. In a hydraulic system, a plunger, fluid operable advancing and. retracting means associated with said plunger for reciprocating the same, first valve means associated with said retracting means and operable in response to a predetermined low pressure on said retracting means to establish fluid communication between said retracting means and said advancing means, and second valve means normally preventing fluid communication between said retracting means and an exhaust but adapted in response to a predetermined high pressure on said advancing means to establish fluid connection between said retractin means and said, exhaust. i

3. In a hydraulic system, a plunger, fluid operable advancing and retracting means. associated with said plunger for reciprocating the same, a pressure fluid source for selectively supplying pressure fluid to said advancing or said retractin; means for actuating the same, conduit means adapted to effect fluid connection between said retracting means and said advancing means, first valve means for controlling said fluid connection,

said valve means including a spring urged plunger normally urged into its closing position for preventing said. fluid connection, and second valve means associated with said retracting means and comprising a'spring urged valve member-continuously urged toward position to prevent fluid communication between said retracting means and an exhaust, said valve member also having fluid operable means associated therewith in fluid communication, with said advancing means and.

responsive to a predetermined pressure to move. said valve member into Position to establish fluid communication between said retracting means and an exhaust.

4. In a hydraulic system, a cylinder, a diflerential plunger with a small and an opposed larger differential area, said plungerbeing'reciprocably mounted in said cylinder, a fluid pressure source for selectively supplying pressure. fluid to one; or

the other of said differential areas for reciprocating said, plunger, conduit means adapted to efiect fluid communication between said difler ential areas, low pressure responsive valve. means normally preventing. said fluid communication on said larger area to effect pressure responsive means and operable in rebut adapted in response to a predeterminedlow pressureon said small area during the advancing stroke of said plunger to eifect said fluid com munication, and high pressure responsive valve means normally preventing fluid connection between said small area and an exhaust but adapted in response to a predetermined high pressure said fluid connection.

5. In a hydraulic system, a cylinder, a differential plunger reciprocably mounted in said cylinder, said diflerential plunger having a large area and anop posed smaller area, a pressure fluid source for selectively supplying pressure fluid. to said large or to said smaller area for reciprocating said plunger, conduit means adapted to effect fluid communication. between said large area. and said smaller area, valve means for con.- trolling said fluid communication, said valve means including a check valve for allowing flow of fluid from said smaller area to said large area while preventing the flow of fluid in thereverse direction, saidvalve means also including a spring urged plunger continuously urged toward its closing position in which said fluid communication isprevented, and high pressure responsive valve means normally preventing fluid connection between said smaller area and an exhaust but adapted to effect said fluid connection in response to 'a predetermined pressure acting on said large area.

6. In a hydraulic system, a cylinder, a plunger reciprocably mounted in said cylinder, said plunger having associated therewith fluid operable advancing means and fluid operable retracting means, the effective area of said fluidl operable retracting means being smaller than the effective area of said fluid operable advancing means, a fluid. source for selectively supplying pressure fluid to said advancing means or to said. retracting means, low pressure responsive exhaust, and means associated with said lowsponse to the supply of pressure fluid from said fluid source to said retracting means for preventing fluid communication between said advancing means and said retracting means.

7. In a hydraulic system, a plunger, fluid operable advancing and retracting means associated with said plunger for reciprocating. the same, the effective area of said advancing means pressure on said retracting means during the advancing stroke of said plunger to effect said fluid communication, yielding means for continuously urging said low pressure responsive means into its closing position to prevent said fluid communication, means responsive to the supply of pressure fluid from said fluid source to said retracting means to convey pressure fluid to said low pressure responsive means to thereby aid said yielding meansin its closing action, and high pressure responsive means normally preventing fluid connection between said retracting means and an exhaust but adapted in response'to a predetermined high pressure on said advancing means for establishing said fluid connection.

8. In a hydraulic system, a plunger, fluid operable-advancing and retracting means associated with said plunger for reciprocating the same, the efiective area of said advancing means being larger than the eflective area of said retracting means, a fluid pressure source for selectively supplying pressure fluid to said advancing means or to said retracting means, conduit means adapted to effect fluid communication between said advancing means and said retracting means, low pressure responsive valve means adapted in response to a predetermined low pressure on said retracting means during the advancing stroke of said plunger to efiect said fluid communication, yielding means for continuously urging said valve means into its closing position to prevent said fluid communication, means responsive to the supply of pressure fluid from said fluid source to said retracting means to convey pressure fluid to said valve means to thereby aid said yielding means in its closing actionghigh pressure responsive means normally preventing fluid connection between said retracting means and an exhaust but adapted in response to a predetermined high pressure on said advancing means to establish said fluid connection, and check valve means interposed between said retracting means and said low pressure valve means and adapted to allow the flow of fluid from said retracting means to said low pressure responsive valve means while preventing the flow of fluid in the reverse direction.

9. In a hydraulic system, a. plunger, fluid operable advancing and retracting means for reciprocating said plunger, the effective area of said retracting means being smaller than the effective area of said advancing means, a fluid pressure source for selectively supplying pressure fluid to said advancing means or to said retracting means, first valve means responsive to a predetermined low. pressure on said retracting means during the advancing stroke of said plunger for establishing fluid'connection between said advancing and said retracting means, sec- 0nd valve means'associated with said retracting means and normally preventing fluid communication between said retracting means and an exto a predetermined pressure on said advancing means to effect said fluid communication, and control means responsive to the supply of pressure from said fluid source to said retracting means for preventing fluid connection between said retracting means and said advancing means.

10. In a hydraulic system, a reciprocable plunger having a main area and a diflerential area associated therewith, means for supplying actuating fluid to said main area or to said differential area for reciprocating said plunger, flrst valve means normally preventing fluid communication between said difierential area and exhaust and operable in response to a predetermined pressure on said main area to connect said differential area to exhaust, and a second valve WALTER ERNST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Stacy June 1, 1943 

